Controlling flow is an important and useful tool in virtually all scientific fields. One such field where controlling flow is highly useful is in the medical arena. For example, it may be useful to control flow during infusion, e.g., when introducing fluid into a blood vessel, such as a vein, via a fluid line for therapeutic and/or diagnostic purposes. The fluid introduced may be saline solution, plasma solution, glucose solution, antibiotics, pain relievers, nuclear medicine agents, and the like. Infusion may involve many fluid doses into a patient over long periods of time. Early in the infusion field, each fluid dose required a new needle to be inserted into the vein. Repeated insertion of a needle into the same vein of a patient, however, may damage the vein, increase the potential for bruising, and/or inflict pain on or discomfort to the patient.
Health professionals quickly changed this routine by inserting one needle into the patient's vein, and leaving it there for initial and subsequent fluid dose introductions. This stationary needle could be connected to a first or proximal end of a catheter that had an opening at a second or distal end for receiving fluid from a syringe or other device. For example, a latex cap was placed over the distal end of the catheter, which could be penetrated by a beveled hollow needle. Once inserted into the patient's vein, the stationary needle could be secured with tape, but was prone to disconnection from the patient. From this basic concept, a range of needleless connectors were developed capable of linking the fluid line to the patient's catheter directly thereby bypassing needle use. Further industry directive and federal regulation encouraged this alternative technique of promoting needleless connectors' use, thereby promoting removal of sharp instruments from the patient area.
Early needleless connectors featured a split septum on the female end (e.g., the end closer to the patient during connection). The split septum could be opened by inserting a cannula. The male end featured a blunt cannula, which was inserted into the split-septum on the female end. This method relieved some of the disconnection problems, but a new problem emerged. Removing the blunt cannula created a negative pressure inside the catheter, which caused a small amount of blood from the patient to flow into the proximal end of the catheter. These small amounts of blood would accumulate in the catheter, thereby clogging the fluid pathway. The consequence of this negative pressure, or negative bolus effect, was to require a new, clean catheter. The replacement of these clogged catheters may be expensive and/or painful to the patient.
The split septum on the female end was then replaced with an anti-reflux valve activated by the use of a male-female Luer configuration, also termed sequential valving. This male-female Luer connection has been standardized by the industry, e.g., through international standard ISO 594-2 “Conical fittings with a 6% (Luer) taper for syringes, needles and certain other medical equipment”, Part 2: Lock fittings.
The demand for closed needleless systems for fluid administration is driven, at least partially, by the safety concerns associated with medications that are toxic to healthcare workers that prepare and administer these medications. These medications include chemotherapy and radiotherapeutic agents. Key industry organizations, such as the National Institute for Occupational Safety and Health (NIOSH), Oncology Nursing Society (ONS), and American Society of Health System Pharmacists (ASHP), recommend adopting closed systems to minimize drips, leaks, or spills of the drug to help eliminate surface contamination and exposure.
The vast majority of the self-sealing medical connectors that are used for the administration of parenteral fluids are designed with an unsealed male Luer connector on the end that remains connected to the patient's IV line, fluid source, etc., and a female connector on the opposite free end of the connector through which a syringe or other types of devices is connected. In many devices on the market, there is a self sealing valve built into the female connector. The male Luer typically does not have an internal valve, and as such, any remaining fluid is capable of being exposed to care providers and/or patients upon disconnection of the unsealed male Luer. As mentioned above, for certain applications, the fact that residual volume of the fluid may be unsealed and/or exposed to individuals around the IV system may pose significant health hazards. Additionally, these conventional Luer connectors may have a larger internal volume in which fluid may collect, and also employ many parts thereby increasing the potential for error in manufacturing or during use.
The standard connection mechanism for these Luer connectors involves aligning the threads together by a helical threading action. This threading action is meant to establish a connection between (e.g., engage) the two Luer ends, and is not the force used to open or close (e.g., actuate) fluid pathways. As the two Luer connectors are being connected together, there is a separate translational (e.g., on a vertical axis) action within these connection assemblies that acts to engage the fluid pathways. Traditionally, the female end has a thread on the outside while the male has a thread on the inside. Since most female ends have self-sealing valves, the user may open the fluid path with the translational force during engagement or after the male end is completely engaged and locked inside the female end. Thus, the user may not know at what point the fluid path is sufficiently opened or closed during connection and disconnection of the two connectors. The user only knows that the fluid path is closed (e.g., the two connectors are deactuated), when the two connectors are completely disengaged, or disconnected, and separated.
Thus, there is a need in the art for a connector and/or connecting assembly that may effectively avoid uncertainty in the actuation process, avoid certain undesired pressure effects, create certain desired pressure effects, reduce the internal volume of the assemblies, and/or decrease the number of members required for manufacturing.